5-Mononitro-2,3,7,8,12,13,17,18-octaethylporphyrin, 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin, and their Cd(II) complexes were synthesized. The coordination reactions of 2,3,7,8,12,13,17,18-octaethylporphyrin and its mono- and trinitro-substituted derivatives and the metal-exchange reactions of the synthesized Cd(II) octaethylporphyrin complexes with Mn(II) chloride in DMF were investigated by spectrophotometry. The corresponding Mn(II) and Mn(III) porphyrins were obtained and identified. The kinetic parameters of the studied reactions were determined.